The present disclosure is related to the field of optical fibers. Specifically, the disclosure relates to fiber optic rotary joints for dual-core fibers.
Optical fiber systems are often utilized for information transmission from a down-hole location during run-in-hole (“RIH”) operations. It is common to stop during the RIH and manually connect to a fiber optic sensing cable to perform health checks of the fiber optic sensing systems. Ordinarily, this process involves stopping deployment, securing the reel, and manually connecting optical fibers to take a measurement. This process requires the deployment to be stopped and the rig placed into a standby period while the optical systems are being tested. This stoppage increases the operational and deployment costs of the system.
Oftentimes, where numerous downhole sensing systems exist, a single channel fiber optic rotary joint is insufficient to allow health checks of all the downhole fiber optic systems. Multi-channel fiber optic slip-rings are sometimes used in the field today to allow rotation of a cable with multiple fibers corresponding to multiple downhole systems. The large majority of these existing optical slip-rings are configured to house multiple single-channel fibers corresponding to multiple downhole systems often consist of complicated arrangements that exacerbate the problems associated with traditional sensing system performance. For example, periodic manual connections may still be needed with these multiple-fiber slip-ring systems, which, as stated above, drive up rig time and production costs. Thus, improved fiber optic rotary joints are needed for multi-system optical sensing applications.